title: Affinity-purified anti-protein I antibody. Specific inhibitor of phosphorylation of protein I, a synaptic protein.
abstract: Protein I is a synaptic protein which serves as an endogenous substrate for cyclic AMP- and calcium-dependent protein kinases. Antibodies raised against purified Protein I have been isolated from rabbit antiserum by affinity chromatography on Protein I-conjugated agarose column. The purified antibodies were identified as immunoglobulin G by sodium dodecyl sulfate polyacrylamide gel electrophoresis and Ouchterlony double immunodiffusion precipitation test. The purified antibodies not only inhibited the phosphorylation of purified Protein I by exogenous cyclic AMP-dependent protein kinase, but also inhibited specifically the phosphorylation of Protein I by endogenous cyclic AMP-dependent protein kinase in a synaptic vesicle fraction, synaptic junctional complex fraction, synaptic membrane fraction, and crude homogenate of cerebrum. The purified anti-Protein I antibodies also inhibited with a similar potency calcium-dependent phosphorylation of Protein I without affecting the phosphorylation of other proteins. The Fab(t) fragment of anti-Protein I immunoglobulin G, which was produced by tryptic digestion, retained the ability to inhibit specifically the phosphorylation of Protein I. This substrate-directed, specific inhibitor of the phosphorylation of Protein I may provide a unique probe for investigating the function of Protein I phosphorylation.
mesh_terms: D000818:Animals; D000906:Antibodies / Q000302:isolation & purification*; D000936:Antigen-Antibody Complex; D001921:Brain / Q000378:metabolism*; D002417:Cattle; D002846:Chromatography, Affinity; D005779:Immunodiffusion; D007074:Immunoglobulin G; D007700:Kinetics; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000276:immunology* / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D013569:Synapses / Q000378:metabolism*; D016704:Synapsins; D013570:Synaptic Membranes / Q000378:metabolism
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D007074:Immunoglobulin G; D009419:Nerve Tissue Proteins; D016704:Synapsins; D011494:Protein Kinases